Breakdown characteristics of gas spark switch for fast linear transformer driver under DC and pulse combined voltage

The breakdown delay processes of gas switches under combined voltages of DC and pulse voltages in the faster linear transformer driver (FLTD) are analyzed. A formula is presented to estimate the delay time. The three-electrode gas switches used in the present FLTD were preliminarily tested under combined voltages to investigate the breakdown characteristics by experiment. The experimental results indicate that, as applying the combined voltage of 70 kV DC voltage and 300 kV/30 ns fast pulse voltage, the delay time of switches under the combined voltages is smaller than that of normal trigger method. When gas switches are insulated by SF6, the delay time decreases by 17%-30%. While the delay time decreases by 50% with N2 as the dielectric. At the working coefficient of 55%, the jitter is less than 5 ns. Moreover, the estimated delay time is in close agreement with the experimental result.